From: Tiwei Bie <tiwei.bie@intel.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: mst@redhat.com, jasowang@redhat.com,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, shahafs@mellanox.com,
rob.miller@broadcom.com, haotian.wang@sifive.com,
eperezma@redhat.com, lulu@redhat.com, parav@mellanox.com,
rdunlap@infradead.org, hch@infradead.org, jiri@mellanox.com,
hanand@xilinx.com, mhabets@solarflare.com,
maxime.coquelin@redhat.com, lingshan.zhu@intel.com,
dan.daly@intel.com, cunming.liang@intel.com,
zhihong.wang@intel.com
Subject: Re: [PATCH] vhost: introduce vDPA based backend
Date: Thu, 20 Feb 2020 10:42:21 +0800 [thread overview]
Message-ID: <20200220024220.GA43609@___> (raw)
In-Reply-To: <20200219131102.GN31668@ziepe.ca>
On Wed, Feb 19, 2020 at 09:11:02AM -0400, Jason Gunthorpe wrote:
> On Wed, Feb 19, 2020 at 10:52:38AM +0800, Tiwei Bie wrote:
> > > > +static int __init vhost_vdpa_init(void)
> > > > +{
> > > > + int r;
> > > > +
> > > > + idr_init(&vhost_vdpa.idr);
> > > > + mutex_init(&vhost_vdpa.mutex);
> > > > + init_waitqueue_head(&vhost_vdpa.release_q);
> > > > +
> > > > + /* /dev/vhost-vdpa/$vdpa_device_index */
> > > > + vhost_vdpa.class = class_create(THIS_MODULE, "vhost-vdpa");
> > > > + if (IS_ERR(vhost_vdpa.class)) {
> > > > + r = PTR_ERR(vhost_vdpa.class);
> > > > + goto err_class;
> > > > + }
> > > > +
> > > > + vhost_vdpa.class->devnode = vhost_vdpa_devnode;
> > > > +
> > > > + r = alloc_chrdev_region(&vhost_vdpa.devt, 0, MINORMASK + 1,
> > > > + "vhost-vdpa");
> > > > + if (r)
> > > > + goto err_alloc_chrdev;
> > > > +
> > > > + cdev_init(&vhost_vdpa.cdev, &vhost_vdpa_fops);
> > > > + r = cdev_add(&vhost_vdpa.cdev, vhost_vdpa.devt, MINORMASK + 1);
> > > > + if (r)
> > > > + goto err_cdev_add;
> > >
> > > It is very strange, is the intention to create a single global char
> > > dev?
> >
> > No. It's to create a per-vdpa char dev named
> > vhost-vdpa/$vdpa_device_index in dev.
> >
> > I followed the code in VFIO which creates char dev
> > vfio/$GROUP dynamically, e.g.:
> >
> > https://github.com/torvalds/linux/blob/b1da3acc781c/drivers/vfio/vfio.c#L2164-L2180
> > https://github.com/torvalds/linux/blob/b1da3acc781c/drivers/vfio/vfio.c#L373-L387
> > https://github.com/torvalds/linux/blob/b1da3acc781c/drivers/vfio/vfio.c#L1553
> >
> > Is it something unwanted?
>
> Yes it is unwanted. This is some special pattern for vfio's unique
> needs.
>
> Since this has a struct device for each char dev instance please use
> the normal cdev_device_add() driven pattern here, or justify why it
> needs to be special like this.
I see. Thanks! I will embed the cdev in each vhost_vdpa
structure directly.
Regards,
Tiwei
>
> Jason
prev parent reply other threads:[~2020-02-20 2:42 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-31 3:36 [PATCH] vhost: introduce vDPA based backend Tiwei Bie
2020-01-31 3:56 ` Randy Dunlap
2020-01-31 5:12 ` Randy Dunlap
2020-01-31 5:54 ` Tiwei Bie
2020-01-31 5:52 ` Tiwei Bie
2020-02-04 3:30 ` Jason Wang
2020-02-04 6:01 ` Michael S. Tsirkin
2020-02-04 6:46 ` Jason Wang
2020-02-05 2:05 ` Tiwei Bie
2020-02-05 3:12 ` Jason Wang
2020-02-05 5:31 ` Michael S. Tsirkin
2020-02-05 5:50 ` Jason Wang
2020-02-05 6:30 ` Michael S. Tsirkin
2020-02-05 6:49 ` Jason Wang
2020-02-05 7:16 ` Michael S. Tsirkin
2020-02-05 7:42 ` Jason Wang
2020-02-05 9:22 ` Michael S. Tsirkin
2020-02-05 2:02 ` Tiwei Bie
2020-02-05 3:11 ` Jason Wang
2020-02-05 7:15 ` Shahaf Shuler
2020-02-05 7:50 ` Jason Wang
2020-02-05 9:23 ` Michael S. Tsirkin
2020-02-06 3:07 ` Jason Wang
2020-02-05 9:30 ` Shahaf Shuler
2020-02-05 10:33 ` Michael S. Tsirkin
2020-02-06 3:09 ` Jason Wang
2020-02-06 3:04 ` Jason Wang
2020-02-05 12:56 ` Jason Gunthorpe
2020-02-05 13:14 ` Michael S. Tsirkin
2020-02-06 3:11 ` Jason Wang
2020-02-06 3:21 ` Zhu Lingshan
2020-02-18 13:53 ` Jason Gunthorpe
2020-02-19 2:52 ` Tiwei Bie
2020-02-19 13:11 ` Jason Gunthorpe
2020-02-20 2:42 ` Tiwei Bie [this message]
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